Doctor of Philosophy

dissertationThree phase ebullieted bed reactors are appropriate for processing petroleum residues, bitumen and bitumen derived liquids. The length of a three phase ebullieted bed reactor, which is long at the commercial scale, can be reduced, for process research and development studies in the laboratory, by decreasing the superficial liquid velocity and solid particle size. It is necessary to maintain same phase holdups of the commercial reactor, to simulate the process kinetics in a laboratory reactor. Similarity criteria that ensured identical phase holdups in commercial and laboratory units were identified, through extensive similitude studies. These criteria required the equality o f six dimensionless numbers. It was impractical to establish all the parameters in the set of dimensionless numbers at the desired values for reacting systems. Therefore, a procedure was developed to achieve similarity by varying a minimum number of parameters, such as liquid and gas superficial velocities and particle size. This resulted in two conditions, which when satisfied yielded essentially equal holdups in the two reactors. These criteria and procedure were validated using the generalized wake model and experimental data for three phase systems. The similitude studies identified the importance of the bubble rise velocity for scale down. Two different approaches were developed to predict the bubble rise velocity in three phase ebullieted beds. In the first approach, a mathematical model was developed to predict the volume of a single bubble generated at an orifice in a gas-liquid system at a constant gas flow rate. The model was based on a rigorous bubble closure mechanism and incorporated the interaction between the primary bubble and subsequent bubbles formed at the orifice at high gas flow rates. The model also calculated the distance traveled by the bubble from the orifice before it detached. The model is applicable for both viscous and nonviscous liquids and for systems over wide ranges of hydrodynamic properties. The model was validated by comparison with the available experimental data and it was found that this model represented an improvement over previous models. This model was used to approximate the value of the bubble size in a high pressure three phase ebullieted bed with small solid particles. In the second approach the concept of effective bubble rise velocity was introduced. The generalized wake model equations were manipulated to give correlations for the effective bubble rise velocity at atmospheric pressure. The parameters for the correlations were liquid and gas superficial velocities, liquid viscosity, surface tension and solid particle size. These correlations were categorized as per the type of three phase system, solid particle size and liquid and gas superficial velocities. Flow transition liquid velocities for various three phase systems were identified. Forms of the correlations were explained by addressing various hydrodynamic phenomena for three phase ebullieted beds such as flow regimes and their transitions, flow transition liquid velocity, solid wettability, bubble behavior, apparent bed viscosity and the effect of solid particles. The performance of the correlations was tested with experimental phase holdup data. The influence of pressure on bubble behavior and bubble rise velocity in a three phase ebullieted bed was considered. This led to the introduction of a pressure factor in the bubble rise velocity correlations. The modified correlations were used to predict the bubble rise velocity in three phase ebullieted bed operating at high temperature and high pressure. The predictions of the modified bubble rise velocity correlations were evaluated, using the concept of drift flux, against experimental plots available from the literature. The trends of drift flux vs. gas holdup in the plots were found satisfactory. Values of the gas and liquid densities, liquid viscosities and surface tensions at high temperature and high pressure were required for reactor scale down. A plot for temperature versus weight fraction distilled up to 813 K was obtained by simulated distillation for the native bitumen. A method was then developed to extrapolate the low temperature (813 K -) SIMDIS curve to high temperature (813 K + ) region by matching the measured value of specific gravity of the native bitumen with the specific gravity calculated from the extrapolated curve. The extrapolated SIMDIS curve was used to develop a predictive correlative procedure for estimating the viscosity and surface tension of bitumen fractions and bitumen at high temperature and high pressure. The predictive method identified a new mixing rule for fractions of heavy feeds, where the viscosities of the individual fractions vary over a few orders of magnitude. An overall procedure for scaling down a commercial three phase ebullieted bed reactor to a laboratory scale was then developed. The procedure ensured reduction in reactor length and maintained identical phase holdups and bubble rise velocity in both the reactors. The space velocity in the laboratory reactor was adjusted to achieve similar intraparticle mass transfer as the commercial reactor. Using the methods mentioned above for calculating the bubble rise velocity and physical properties of the feed and the overall scale down procedure, a detailed design of a laboratory scale three phase ebullieted bed reactor was carried out. This reactor can be used to carry out process development studies for hydrotreating/hydrocracking of bitumens and bitumen derived liquids in the laboratory, under conditions similar to the commercial reactor

Building Resilient Cloud Over Unreliable Commodity Infrastructure

Cloud Computing has emerged as a successful computing paradigm for efficiently utilizing managed compute infrastructure such as high speed rack-mounted servers, connected with high speed networking, and reliable storage. Usually such infrastructure is dedicated, physically secured and has reliable power and networking infrastructure. However, much of our idle compute capacity is present in unmanaged infrastructure like idle desktops, lab machines, physically distant server machines, and laptops. We present a scheme to utilize this idle compute capacity on a best-effort basis and provide high availability even in face of failure of individual components or facilities. We run virtual machines on the commodity infrastructure and present a cloud interface to our end users. The primary challenge is to maintain availability in the presence of node failures, network failures, and power failures. We run multiple copies of a Virtual Machine (VM) redundantly on geographically dispersed physical machines to achieve availability. If one of the running copies of a VM fails, we seamlessly switchover to another running copy. We use Virtual Machine Record/Replay capability to implement this redundancy and switchover. In current progress, we have implemented VM Record/Replay for uniprocessor machines over Linux/KVM and are currently working on VM Record/Replay on shared-memory multiprocessor machines. We report initial experimental results based on our implementation.Comment: Oral presentation at IEEE "Cloud Computing for Emerging Markets", Oct. 11-12, 2012, Bangalore, Indi

New targets for resolution of airway remodeling in obstructive lung diseases.

Airway remodeling (AR) is a progressive pathological feature of the obstructive lung diseases, including asthma and chronic obstructive pulmonary disease (COPD). The pathology manifests itself in the form of significant, progressive, and (to date) seemingly irreversible changes to distinct respiratory structural compartments. Consequently, AR correlates with disease severity and the gradual decline in pulmonary function associated with asthma and COPD. Although current asthma/COPD drugs manage airway contraction and inflammation, none of these effectively prevent or reverse features of AR. In this review, we provide a brief overview of the features and putative mechanisms affecting AR. We further discuss recently proposed strategies with promise for deterring or treating AR

Bitter Taste Receptors for Asthma Therapeutics.

Clinical management of asthma and chronic obstructive pulmonary disease (COPD) has primarily relied on the use of beta 2 adrenergic receptor agonists (bronchodilators) and corticosteroids, and more recently, monoclonal antibody therapies (biologics) targeting specific cytokines and their functions. Although these approaches provide relief from exacerbations, questions remain on their long-term efficacy and safety. Furthermore, current therapeutics do not address progressive airway remodeling (AR), a key pathological feature of severe obstructive lung disease. Strikingly, agonists of the bitter taste receptors (TAS2Rs) deliver robust bronchodilation, curtail allergen-induced inflammatory responses in the airways and regulate airway smooth muscle (ASM) cell proliferation and mitigate features of A

Light scattering from a magnetically tunable dense random medium with weak dissipation : ferrofluid

We present a semi-phenomenological treatment of light transmission through and its reflection from a ferrofluid, which we regard as a magnetically tunable system of dense random dielectric scatterers with weak dissipation. Partial spatial ordering is introduced by the application of a transverse magnetic field that superimposes a periodic modulation on the dielectric randomess. This introduces Bragg scattering which effectively enhances the scattering due to disorder alone, and thus reduces the elastic mean free path towards Anderson localization. Our theoretical treatment, based on invariant imbedding, gives a simultaneous decrease of transmission and reflection without change of incident linear polarisation as the spatial order is tuned magnetically to the Bragg condition, namely the light wave vector being equal to half the Bragg vector (Q). Our experimental observations are in qualitative agreement with these results. We have also given expressions for the transit (sojourn) time of light and for the light energy stored in the random medium under steady illumination. The ferrofluid thus provides an interesting physical realization of effectively a "Lossy Anderson-Bragg" (LAB) cavity with which to study the effect of the interplay of spatial disorder, partial order and weak dissipation on light transport. Given the current interest in propagation, optical limiting and storage of light in ferrofluids, the present work seems topical

Estimation of Leptin Levels in Serum in Periodontal Health and Disease: A Clinical and Biochemical Study

Introduction: Leptin is a hormone secreted by the adipocytes. As the periodontal breakdown increases, leptin concentration in serum increases with the destruction of the periodontium, but the evidence for this association is not so strong. So, the aim of our study was to evaluate the serum leptin levels in healthy, gingivitis and periodontitis group. Materials and methods: Total 75 patients were selected and divided into three groups. Healthy (BOP < 30%, PD ≤ 4 mm), gingivitis (BOP ≥ 30%, PD ≤ 4 mm) and periodontitis (PD ≥ 4 mm). The clinical parameters that evaluated were OHI-S, PI, PD and % of BOP at baseline, 15 days and 1 month. Also, blood was collected from the anticubical fossa and was analyzed for Leptin ELISA test. Results: There was a statistically significant reduction in all clinical parameters at the end of 15 days and 1 month. In healthy group, there was strong association between OHI-S and serum leptin levels. Whereas in gingivitis group, there was a statistically significant association between OHI-S, PD and serum leptin levels than in periodontitis group. Conclusion: In our study, as the periodontal disease progressed, there was raise in serum leptin concentration in gingivitis (p < 0.005) but these results did not remain  consistent for periodontitis group. From, this we can say that for leptin to be an inflammatory marker and risk indicator or risk predictor in the progression of periodontal diseases further studies are needed.&nbsp

Study of Orthopedic Morbidities among Postmenopausal Women in a Medical College Hospital in Rural Area of Western Maharashtra, India

Introduction: It is estimated that a total of 130 million Indian women are expected to live beyond menopause by 2015. Health of postmenopausal women is of growing concern because of increased longevity and various morbidities associated with old age. Objectives: 1) To assess various orthopedic problems among postmenopausal women in rural area. 2) To estimate magnitude of common orthopedic problems and associated sociodemographic factors. Methodology: A cross-sectional study was conducted at the medical college hospital in rural area of Western Maharashtra on 500 postmenopausal women availing healthcare in a medical college hospital. Data was collected with the help of predesigned questionnaire by interview technique and with the help of case records available from orthopedic department. Results: Backache (62%) and osteoarthritis (51.6%) were common orthopedic problems. Osteoarthritis was significantly associated with obesity

Effect of Palmitic Acid on B2 Receptor Expression In Airway Smooth Muscle Cells

Introduction: People with asthma and obesity struggle to control asthma flares. B2 agonists are often the acute treatment of choice during these flares, so the decreased asthma control in this population may be due to a decrease in B2 receptor activity. We tested the hypothesis that B2 receptor expression will decrease in airway smooth muscle cells exposed to Palmitic Acid, a saturated fatty acid, compared to Oleic Acid and untreated cells. Methods: Airway smooth muscle cells were plated and treated with Palmitic Acid and Oleic Acid at 100uM and 200uM concentrations while other untreated cells served as controls. Cells were lysed at 24 and 48 hours and their RNA was harvested for expansion using PCR with B2 and GAPDH primers. RT-PCR was used to quantify RNA expression. GAPDH was used as an expression control to normalize B2 values for each condition and the resulting dCq values for each condition were compared. Results: The Palmitic Acid group did not show significant decrease in B2 expression compared to the control or Oleic Acid groups. This was consistent across all concentrations and time points. There was no significant change in receptor expression for any condition. Discussion: These results did not support our hypothesis that B2 expression would decrease in cells treated with Palmitic Acid. The expression of this receptor and its activity is not regulated as we hypothesized illustrating need to explore other factors that may contribute to the difference of the B2 receptor agonist response in obese people with asthma